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Messages - SonusBonum

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Tape Tech / Re: STUDER A810 SPOOLING MOTOR CONTROL PCB 1.810.760-82
« on: June 13, 2016, 01:20:03 PM »
Hold the phone: not the motor either...! Wobbeling came back. Now I'm angry as a bird...!
Long story short: The brake solenoid wasn't working/moving at all.
That explains the temperature dependency too.

Anyway, finally I can mark this one as solved...!!!

Thank to all for baring with me on this one...

Tape Tech / Re: STUDER A810 SPOOLING MOTOR CONTROL PCB 1.810.760-82
« on: June 12, 2016, 02:21:55 PM »
Oh I forgot: Thank you for responding to my post. It's good to know I am not alone in my R2R adventure... :-)

Tape Tech / Re: STUDER A810 SPOOLING MOTOR CONTROL PCB 1.810.760-82
« on: June 12, 2016, 02:20:14 PM »
Well, with respect to the spooling motor problem:

I've renewed ALL electrolytic capacitors and the three big paper caps. Changed the 200uF for the 100uF too. Still no change to the wobbeling.
I have professional Weller desolder equipment and resoldered with high quality tin with some silver added to it.
Visually checked the board, the voltages, the test points.

So out of frustration I bought another A810 around the corner and guess what: First changed the spooling motor control PCB. Still wobbeling. Than changed the left motor with the one in the "new" A810: NO PROBLEM ANYMORE...?????

I never ever expected the problem to be in the friggin' motor...?! It turns perfectly. I haven't disassembled it yet.

Reel to Reel Tape Machines / Re: PLL Capstan Light on A810
« on: June 10, 2016, 03:20:09 AM »
I experienced the same thing the other day. The PLL light goes on and off in a regular fashion. I am still in the "fault detection phase" but after reading this post I would like to add something that caught my eye.

In the A810 manual it says: "CAUTION Ensure that proper electrical insulation and excellent thermal contact with the heatsink bracket is achieved WHEN REPLACING THE POWER TRANSISTORS (Q1, Q2)..."

What puzzles me is why they added this caution. There are no other similar warnings like that at all.

In other words: since one transistor does the spinning and the other the braking, could it be that this may be my (and your) problem...?

« on: May 25, 2016, 02:36:31 PM »
Hi everyone,

I just got my beautiful A810 and it plays like an angel. However after a while and closer to the end of the tape the left tension roller starts wobbling. It is like the tape tension fluctuates in a regular fashion.
I took out the SPOOLING MOTOR CONTROL PCB and checked it. What I found was that C15, C16, C18 and C18 were 220uF/35V while the book says they must be 100uF/25V. Since those caps are in a opamp circuit I figure that these values should be correct. I mean, they are not just for voltage regulation.
Can someone tell me whether the book is wrong or the guy that changed the caps...?
Thank you much...!


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